The present invention relates to a device and method of forming a custom dental shade guide for matching tooth colored filling material to natural teeth.
Dental shade guides serve the purpose of assisting the dentist in matching a filling, restorative material, or artificial tooth to the patient's existing teeth.
Shade guide assemblies generally consist of a holder from which project a plurality of individual color samples or tabs usually in the shape of a tooth. The dentist chooses from among the group the one tab which most precisely matches the tooth to be restored. A restorative material or artificial tooth is then selected that corresponds in shade to the particular tab chosen.
The early design of shade guides contributed to inaccuracies in color match because the shade tabs were not translucent as are natural teeth. They also had to be positioned in the mouth in such a way as to distort the light reaching the tooth. In 1949, Harvey J. Russell designed a shade guide described in U.S. Pat. No. 2,479,543 for the purpose of correcting these shortcomings, which has more or less become the standard since.
The Russell shade guide and all subsequent modifications are made of a material, usually a heat processed acrylic resin, that bears no relation to the tooth colored filling materials used to restore teeth. Today, the cosmetic materials most commonly used for fillings are chemically and physically different from the material of which the colored tab of the shade guide is made. More specifically, these restorative materials differ from the shade tabs in their optical properties and characteristics, that is, the way in which they reflect, refract, and transmit light. It is this difference between the composition of the shade guide tab and that of the filling material itself, which accounts for the greatest source of error in shade selection.
Manufacturers of the various restorative filling materials either provide their own shade guide with the materials they sell or provide a reference to one of the standard shade guides used in selecting artificial teeth. In either case, the actual filling material, being of different composition from the colored portion of the shade guide tab, seldom matches the tab due to the inherent differences in the optical properties of the materials. Furthermore, none of the shade guides indicate what the resulting combination of two or more restorative materials will look like when mixed.
One way around this problem, has been the practice of some dentists to take a sample of the filling material to be used, and place it next to the tooth to be restored, in order to determine if the shade will match. This method eliminates the use of the shade guide. However, if the shade is not correct, the sample material taken from the supply tube must be discarded since the syringe type dispensers of the new filling materials do not provide for material to be replaced once extruded from the tube. This can be a rather costly practice. Furthermore, it is sometimes necessary to obtain the proper shade by mixing two or more different shades of materials. If the resulting color is inadequate, this material also must be discarded.
It is an object of the present invention to provide a device and method which allows the dentist to form the restorative material that he will be using to repair a tooth, directly into a shade tab so as to facilitate an accurate color match.
It is another object of this invention to provide a device and method which utilizes a sample of the filling material itself in forming the colored portion of the shade tab. Since a shade tab thus formed is an exact color match of the filling material and can be used repeatedly for subsequent color matches, it is more practical than the methods being used today.
It is still another object to provide a device and method whereby the individual dentist may form a shade tab for each of the pure colors of filling material generally used by the dentist as well as for selected combinations of filling materials and thereby create a custom shade guide mounted assembly of various shades.
The number of shade combinations that may be incorporated into tabs will increase quantitatively and qualitatively the sample selection from which a dentist may choose an appropriate match between filling material and tooth to be restored and the shade tabs thus formed will be more representative of what can be reproduced from the filling materials on hand.
These objects, advantages and benefits as well as others will be readily apparent from the following disclosure.